A solid-state lithium-ion battery positive electrode material, a preparation method and application thereof

Abstract

This invention discloses an all-solid-state lithium-ion battery cathode material, its preparation method, and its application. The all-solid-state lithium-ion battery cathode material includes an electrode material body and a coating layer covering the outer layer of the electrode material body. The material of the coating layer is Li. 1+ x Nb 1‑x Ti x O3 (where 0.1 ≤ x < 0.8), and the Ti and Nb elements in the coating layer exhibit segregation, with Ti located closer to the main electrode material and Nb located further away. Based on the total weight of the all-solid-state lithium-ion battery cathode material, the outer coating layer has a mass of 0.25-2 wt% in the dried gel, and its thickness is 2-20 nm. This invention improves the specific capacity and cycle performance of all-solid-state lithium-ion batteries under high voltage and wide temperature range conditions through both coating and activation of elemental segregation.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery cathode material technology, and relates to an all-solid-state lithium-ion battery cathode material, its preparation method and application, and more specifically to an all-solid-state lithium-ion battery cathode material suitable for high voltage and wide temperature range and its preparation method. Background Technology

[0002] With the rapid development of technology, the increasing energy density and safety requirements of new energy vehicles and various industrial production equipment, as well as the demands of special working environments, mean that existing lithium battery systems cannot adequately meet these growing needs. New, safer energy storage systems suitable for these special environments urgently need to be developed and utilized. All-solid-state sulfide-based batteries have attracted considerable attention due to their high energy density, safety, and low pollution levels. However, existing sulfide-based all-solid-state lithium-ion battery systems cannot withstand high voltages. Furthermore, all-solid-state lithium-ion batteries experience severe performance degradation in extreme cold or high temperature environments.

[0003] Using LiCoO2 as the cathode material is an effective way to improve the energy density of sulfide-based all-solid-state lithium-ion batteries. However, in high-voltage operating ranges (greater than 2V, even greater than or equal to 4.5V) and in extreme temperature environments (extremely low or high), LiCoO2 as a cathode material has the following problems: 1. LiCoO2 undergoes irreversible phase transitions and crystal structure collapse, transforming from O3 to H1-3 phase, and eventually to O1 or rock salt phase; 2. LiCoO2 experiences significant stress during charging and discharging, leading to crystal plane cracking and severe interfacial side reactions, resulting in rapid capacity decay; 3. Due to the space charge layer effect at the interface between lithium cobalt oxide and the sulfide solid electrolyte, a carrier disappearance layer exists at the cathode interface, making it difficult for lithium ions to undergo effective ion transport at the interface.

[0004] To address the above problems, this invention is proposed. Summary of the Invention

[0005] This invention first coats LiCoO2 cathode material with Li on the outer layer. 1+x Nb 1-x Ti x The O3 coating effectively suppresses the irreversible phase transition and interfacial side reactions between the oxide cathode (LiCoO2) and the sulfide all-solid electrolyte. Additionally, Li... 1+x Nb 1-x Ti xThe presence of the O3 coating layer can also promote lithium-ion transport at the positive electrode interface, initially improving the specific capacity and cycle life of the all-solid-state lithium-ion battery under high voltage and wide temperature range operation in three aspects, enabling it to express its capacity normally during charge and discharge. Furthermore, this invention utilizes high voltage to activate the coating layer, causing Ti and Nb elements to segregate within the coating layer, further improving the specific capacity and cycle performance of the all-solid-state lithium-ion battery under high voltage and wide temperature range operation.

[0006] The purpose of this invention is to provide a cathode material for all-solid-state lithium-ion batteries suitable for high voltage (2-4.5V) and wide temperature range (-20-80℃) and its preparation method, so as to meet the current demand for all-solid-state lithium-ion battery production.

[0007] To achieve the above objectives, the technical solution proposed by this invention is as follows:

[0008] The first aspect of this invention provides an all-solid-state lithium-ion battery cathode material, the all-solid-state lithium-ion battery cathode material comprising an electrode material body and a coating layer covering the outer layer of the electrode material body, the coating layer being made of Li. 1+x Nb 1-x Ti x O3 (where 0.1≤x<0.8), and the Ti and Nb elements in the coating layer are segregated in the coating layer, wherein the Ti element is located closer to the main body of the electrode material, and the Nb element is located away from the main body of the electrode material; based on the total weight of the all-solid-state lithium-ion battery cathode material, the mass of the outer coating layer in the dry gel is 0.25-2wt%, and the thickness of the coating layer is 2-20nm.

[0009] Preferably, the oxide cathode material of the all-solid-state lithium-ion battery is lithium cobalt oxide (LiCoO2).

[0010] A second aspect of the present invention provides a method for preparing the all-solid-state lithium-ion battery cathode material described in the first aspect of the present invention, comprising the following steps:

[0011] (1) Add lithium source, niobium source and titanium source to organic alcohol solution according to the metric ratio, stir continuously, add electrode material body and continue stirring to form sol;

[0012] (2) The sol obtained in step (1) is stirred and the solvent organic alcohol is evaporated under constant temperature and vacuum, and dried to form a gel; and

[0013] (3) The gel obtained in step (2) is calcined at a constant temperature and cooled in the furnace to obtain a precursor of all-solid-state lithium-ion battery cathode material;

[0014] (4) The all-solid-state lithium-ion battery cathode material precursor obtained in step (3) is activated during the first voltage cycle charge and discharge process to cause the segregation of Ti and Nb elements, thereby obtaining the all-solid-state lithium-ion battery cathode material.

[0015] Preferably, in step (1), the lithium source is selected from lithium metal or organolithium, the organolithium including alkyl lithium such as lithium ethoxide, lithium isopropoxide or tert-butyllithium, the niobium source is selected from organoniobium or NbCl5, the organoniobium including niobium ethoxide, the titanium source is selected from organotitanium, the organotitanium including isopropyl titanate, tetraethyl titanate or n-butyl titanate; the organic alcohol is selected from one of ethanol, propanol or ethylene glycol; step (1) is carried out in an argon atmosphere, the total stirring time is 1-24h; the molar ratio of lithium source, niobium source, titanium source and organic alcohol is (1-5):(0.1-0.9):(0.1-0.8):(200-5000).

[0016] Preferably, in step (2), the solvent is stirred and evaporated under high temperature vacuum at 40-120℃ for 10-48 hours.

[0017] Preferably, in step (3), the calcination is carried out at a constant temperature under an oxygen flow atmosphere, the heating rate during the calcination process is 1-5℃ / min, the calcination temperature is 300-700℃, and the calcination time is 2-8h.

[0018] Preferably, in step (4), the first voltage is greater than or equal to 4.5V, and the activation time is 0.5-48h.

[0019] The third aspect of the present invention provides an application of the all-solid-state lithium-ion battery cathode material described in the first aspect of the present invention in a sulfide all-solid-state lithium-ion battery, characterized in that the assembled battery operates in a wide temperature range of -20 to 80°C and a high voltage range of 2 to 4.5V.

[0020] The fourth aspect of the present invention provides a method for improving the performance of an all-solid-state lithium-ion battery in a high-voltage operating range, characterized in that the all-solid-state lithium-ion battery cathode material described in the first aspect of the present invention is used as the cathode material of the battery, so as to improve the specific capacity and cycle performance of the all-solid-state lithium-ion battery in a high-voltage operating range of 2 to 4.5V.

[0021] The fifth aspect of the present invention provides a method for improving the performance of an all-solid-state lithium-ion battery in a wide temperature range, characterized in that the all-solid-state lithium-ion battery cathode material described in the first aspect of the present invention is used as the cathode material of the battery to improve the specific capacity and cycle performance of the all-solid-state lithium-ion battery in a wide temperature range of -20 to 80°C.

[0022] In this invention, cycle performance refers to cycle life and cycle stability. Cycle life refers to the retention rate of specific capacity after multiple cycles, while cycle stability refers to the consistent stability of specific capacity during each cycle.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. This invention provides an all-solid-state lithium-ion battery cathode material with an outer coating layer. The all-solid-state lithium-ion battery cathode material includes an electrode material body and a coating layer covering the outer layer of the electrode material body. The material of the coating layer is Li. 1+x Nb 1-x Ti x O3 (where 0.1 ≤ x < 0.8), and the Ti and Nb elements in the coating layer are segregated in the coating layer, with the Ti element located closer to the electrode material body and the Nb element located farther away from the electrode material body; based on the total weight of the all-solid-state lithium-ion battery cathode material, the outer coating layer has a mass of 0.25-2 wt% in the dry gel, and the thickness of the coating layer is 2-20 nm. That is to say, the all-solid-state lithium-ion battery cathode material of the present invention has two characteristics: first, the outer layer of the electrode material body has Li... 1+x Nb 1-x Ti x O3 (where 0.1≤x<0.8) coating layer, the Ti and Nb elements in the second coating layer are segregated in the coating layer.

[0025] This invention first coats LiCoO2 cathode material with Li on the outer layer. 1+x Nb 1-x Ti x The O3 coating effectively suppresses the irreversible phase transition and interfacial side reactions between the oxide cathode (LiCoO2) and the sulfide all-solid electrolyte. Additionally, Li... 1+x Nb 1-x Ti x The presence of the O3 coating layer can also promote lithium-ion transport at the positive electrode interface, initially improving the specific capacity and cycle life of the all-solid-state lithium-ion battery under high voltage and wide temperature range operation in three aspects, enabling it to express its capacity normally during charge and discharge. Furthermore, this invention utilizes high voltage to activate the coating layer, causing Ti and Nb elements to segregate within the coating layer, further improving the specific capacity and cycle life of the all-solid-state lithium-ion battery under high voltage and wide temperature range operation.

[0026] 2. Activating the coating layer with high voltage causes segregation of Ti and Nb elements, which can improve the specific capacity of the all-solid-state lithium-ion battery in the high-voltage operating range. As can be seen from Example 6, the Li-coated...1+x Nb 1- x Ti x O3 can improve the specific capacity of a battery to some extent, but the effect is not very significant. However, after activating it at 4.5V and then applying it to a higher voltage of 4.3V, the specific capacity of the battery is significantly improved, indicating that the elemental segregation that occurs during activation is beneficial to improving the specific capacity of the battery.

[0027] 3. Activating the coating layer with high voltage causes segregation of Ti and Nb elements, which can improve the specific capacity and cycle performance of all-solid-state lithium-ion batteries in extreme temperature operating ranges such as low and high temperatures. As can be seen from Examples 7-8, the Li-coated... 1+x Nb 1-x Ti x O3 can improve the specific capacity of a battery to a certain extent. Further activation at 4.5V followed by application to operating ranges of -20℃ and 80℃ significantly improves the specific capacity, indicating that elemental segregation during activation is beneficial for improving the specific capacity under both low and high temperature operating conditions. More importantly, battery samples assembled with uncoated cathode materials exhibit poor cycle life at both low and high temperatures, with a significant decrease in specific capacity after 10 cycles, while those with Li coating show improved performance. 1+x Nb 1-x Ti x O3 materials can significantly improve cycle life, but cycle stability still needs improvement, with specific capacity fluctuating at different cycle counts. Furthermore, battery samples with activated coatings not only exhibit good cycle life with minimal change in specific capacity after 50 cycles, but also show significantly improved cycle stability compared to unactivated coated samples, with almost no change in specific capacity during each cycle, demonstrating high stability.

[0028] 4. The cathode material described in this invention has the advantages of excellent properties, simple synthesis, and cheap and readily available raw materials. It is suitable for mass production and has universality. It is also suitable for high voltage and wide temperature range environments and is applicable to general commercial lithium cobalt oxide and ternary cathode materials, and has certain commercial prospects. Attached Figure Description

[0029] Figure 1 This is a TEM image of the coated and activated cathode material sample 1 in Example 1;

[0030] Figure 2 This is a SEM image of the coated and activated cathode material sample 1 in Example 1;

[0031] Figure 3 XPS depth analysis of the coated and activated cathode material sample 5 in Example 5, wherein Figure 3a refers to the Ti 2p XPS signal of the Ti element. Figure 3 b refers to the Nb 3d XPS signal of the Nb element.

[0032] Figure 4 Differential phase difference scanning transmission electron microscopy (DPC-STEM) analysis of the coated and activated cathode material sample 5 in Example 5 and the cathode material comparison sample with lithium niobate coating. Figure 4 a and Figure 4 b is Li 1+x Nb 1-x Ti x DPC diagram of O3 coating layer and corresponding electromagnetic field distribution diagram; while Figure 4 c and 4d are the DPC diagrams and corresponding electromagnetic field distribution diagrams of the lithium niobate coating.

[0033] Figure 5 The graph shows the cycle performance of batteries assembled with different cathode material samples in comparative examples and Example 1 at 4.3V and 25°C.

[0034] Figure 6 The graph shows the cycle performance of batteries assembled with different cathode material samples in comparative examples and Example 1 at 4.5V and 25°C.

[0035] Figure 7 The graph shows the cycle performance of batteries assembled with different cathode material samples in comparative examples and Example 1 at -20°C and 4.3V.

[0036] Figure 8 The graph shows the cycle performance of batteries assembled with different cathode material samples in Comparative Examples and Example 1 at 80°C and 4.3V.

[0037] Figure 9 The graph shows the cycle performance of batteries assembled with different cathode material samples in comparative examples and Example 1 at -20°C and 4.5V.

[0038] Figure 10 The graph shows the cycle performance of batteries assembled with different cathode material samples in comparative examples and Example 1 at 80°C and 4.5V.

[0039] Figure 11 The graph shows the cycle performance of the battery assembled from sample 2 (coated and activated positive electrode material) in Example 2 at 25°C and operating at 4.5V.

[0040] Figure 12 The graph shows the cycle performance of the battery assembled from sample 3 (coated and activated positive electrode material) in Example 3 at 25°C and operating at 4.5V.

[0041] Figure 13The graph shows the cycle performance of the battery assembled from sample 4 (coated and activated positive electrode material) in Example 4 at 25°C and operating at 4.5V. Detailed Implementation

[0042] The present invention will be described below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Experimental methods not specifically described in the embodiments generally use conventional conditions and conditions described in the manual, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified. The raw materials used in the following embodiments and comparative examples are all commercially available.

[0043] Comparative Example

[0044] The comparative example is an uncoated lithium cobalt oxide cathode material.

[0045] In this comparative example, the full cell is: cathode lithium cobalt oxide-Li 5.5 PS5Cl 1.5 Sulfide-based all-solid-state electrolyte - Li / In alloy, abbreviated as LCO / LPSCl / In-Li, is a comparative sample.

[0046] Example 1: Preparation of Cathode Material Samples

[0047] The method for coating and modifying the cathode material of an all-solid-state lithium-ion battery described in this embodiment is specifically operated as follows:

[0048] (1) In a glove box filled with argon, lithium ethanol, niobium ethanol and tetrabutyl titanate were added to 3 mL of anhydrous ethanol in a stoichiometric ratio of 1.2:0.8:0.2. The mixture was stirred thoroughly to dissolve the ethanol. Then, lithium cobalt oxide cathode powder was added. The ratio of the amount added to the amount of each raw material was 188:1. The mixture was stirred thoroughly for 12 h to prevent the cathode powder from agglomerating.

[0049] (2) Transfer the sol obtained in (1) to a rotary evaporator, set the temperature to 70°C, and continuously stir and sonicate to prevent aggregation until a gel is formed.

[0050] (3) The gel obtained in (2) was placed in a tube furnace and calcined at a temperature of 350°C for 2 hours under oxygen flow conditions. The heating rate was set to 5°C / min. After cooling, sample 1, which only coated the unactivated positive electrode material, was obtained.

[0051] The unactivated cathode material sample 1 was activated at a high voltage of 4.5V for 24 hours to obtain the coated and activated cathode material sample 1.

[0052] In this embodiment, the full cell differs from the comparative full cell only in the positive electrode material. The battery with sample 1, which only has an unactivated positive electrode material coated on it, as the positive electrode is abbreviated as Li. 1+x Nb1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (unactivated), the battery abbreviated as Li using the coated and activated cathode material sample 1 as the cathode. 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (activated). The cathode materials obtained in Examples 2-5 were named similarly.

[0053] Figure 1 This is a TEM image of the all-solid-state lithium-ion battery cathode material with an outer coating layer in Embodiment 1 of the present invention. The TEM image clearly distinguishes the coating layer and the cathode material lithium cobalt oxide. Figure 2 The image shows an SEM image of the all-solid-state lithium-ion battery cathode material with an outer coating layer in Embodiment 1 of the present invention. The SEM image clearly shows that the size of the lithium cobalt oxide cathode material is at the micrometer level.

[0054] Example 2: Preparation of Cathode Material Samples

[0055] The method for coating and modifying the cathode material of an all-solid-state lithium-ion battery described in this embodiment is specifically operated as follows:

[0056] (1) In an argon-filled glove box, lithium metal, niobium ethanol and isopropyl titanate were added to 4 mL of anhydrous propanol in a stoichiometric ratio of 1.45:0.55:0.45. The mixture was stirred thoroughly to dissolve the materials. Then, lithium cobalt oxide cathode powder was added. The ratio of the amount added to the amount of each raw material was 200:1. The mixture was stirred thoroughly for 24 h to prevent the cathode powder from agglomerating.

[0057] (2) Transfer the sol obtained in (1) to a rotary evaporator, set the temperature to 100°C, and continuously stir and sonicate to prevent aggregation until a gel is formed.

[0058] (3) The gel obtained in (2) was placed in a tube furnace and calcined at 600°C for 6 hours under oxygen flow conditions. The heating rate was set to 3°C / min. After cooling, the sample was activated at a high voltage of 4.5V for 48 hours to obtain the coated and activated positive electrode material sample 2.

[0059] Example 3: Preparation of Cathode Material Samples

[0060] The method for coating and modifying the cathode material of an all-solid-state lithium-ion battery described in this embodiment is specifically operated as follows:

[0061] (1) In a glove box filled with argon, lithium metal, niobium ethanol and isopropyl titanate are added to 5 mL of anhydrous ethylene glycol in a stoichiometric ratio of 1.5:0.5:0.5 and stirred thoroughly to dissolve them. Then, lithium cobalt oxide cathode powder is added, with the ratio of the amount added to the amount of each raw material being 195:1. Stir thoroughly for 15 hours to prevent the cathode powder from agglomerating.

[0062] (2) Transfer the sol obtained in (1) to a rotary evaporator, set the temperature to 90°C, and continuously stir and sonicate to prevent aggregation until a gel is formed.

[0063] (3) The gel obtained in (2) was placed in a tube furnace and calcined at 450°C for 4 hours under oxygen flow conditions. The heating rate was set to 1°C / min. After cooling, the sample was activated at a high voltage of 4.5V for 24 hours to obtain the coated and activated positive electrode material sample 3.

[0064] Example 4: Preparation of Cathode Material Samples

[0065] (1) In a glove box filled with argon, lithium metal, niobium ethanol and isopropyl titanate were added to 3 mL of anhydrous ethanol in a stoichiometric ratio of 1.6:0.4:0.6. The mixture was stirred thoroughly to dissolve the ethanol. Then, lithium cobalt oxide cathode powder was added. The ratio of the amount added to the amount of each raw material was 200:1. The mixture was stirred thoroughly for 2 hours to prevent the cathode powder from agglomerating.

[0066] (2) Transfer the sol obtained in (1) to a rotary evaporator, set the temperature to 80°C, and continuously stir and sonicate to prevent aggregation until a gel is formed.

[0067] (3) The gel obtained in (2) was placed in a tube furnace and calcined at 450°C for 2 hours under oxygen flow conditions. The heating rate was set to 5°C / min. After cooling, the sample was activated at a high voltage of 4.5V for 24 hours to obtain the coated and activated positive electrode material sample 4.

[0068] Example 5: Preparation of Cathode Material Samples

[0069] The method for coating and modifying the cathode material of an all-solid-state lithium-ion battery described in this embodiment is specifically operated as follows:

[0070] (1) In a glove box filled with argon, lithium metal, niobium ethanol and isopropyl titanate were added to 3 mL of anhydrous ethanol in a stoichiometric ratio of 1.175:0.645:0.4. The mixture was stirred thoroughly to dissolve the ethanol. Then, LiCoO2 cathode powder was added. The ratio of the amount added to the amount of each raw material was 260:1. The mixture was stirred thoroughly for 2 hours to prevent the cathode powder from agglomerating.

[0071] (2) Transfer the sol obtained in (1) to a rotary evaporator, set the temperature to 80°C, and continuously stir and sonicate to prevent aggregation until a gel is formed.

[0072] (3) The gel obtained in (2) was placed in a tube furnace and calcined at 400°C for 2 hours under oxygen flow conditions. The heating rate was set to 5°C / min. After cooling, the finished product was obtained. The product was then charged to 4.5V and activated for 5 hours to obtain a coated and activated positive electrode material sample 5.

[0073] The coated LiCoO2 cathode material obtained in this embodiment shows significant optimization and improvement in both cycle performance and compatibility with sulfide-based solid electrolytes in all-solid-state lithium-ion batteries.

[0074] To verify that the amorphous coating layer prepared in this embodiment undergoes elemental segregation in the positive electrode coating layer during the 4.5V LiCoO2 high-voltage charge-discharge cycle, in which Ti... 4+ It will segregate to the LiCoO2 surface, stabilize the lattice oxygen, and gradually form a stable spinel structure in LiCoO2, while Nb 5+ This will cause segregation and enrichment around the coating layer. We used XPS depth technology to analyze Li... 1+ x Nb 1-x Ti x The composition of the cathode interface after electrochemical cycling of O3@LCO / LPSCl / In-Li was investigated, and the results are as follows: Figure 3 .

[0075] Figure 3 XPS depth analysis was performed on sample 5 of the coated and activated cathode material, in which... Figure 3 a refers to the Ti 2p XPS signal of the Ti element. Figure 3 b refers to the Nb 3d XPS signal of the Nb element. Combined with... Figure 3 a and Figure 3 As can be seen from b, before etching, the coating layer of the cathode material sample after coating and activation at 4.5V for 24 hours shows no Ti 2p XPS signal, only Nb 3d XPS signal. This result indicates that Nb in the coating layer... 5+Segregation to the outer layer of the nano-coating layer. After argon ion etching of 5 nm on the coating layer of the above cathode sample, XPS depth analysis was performed again, revealing a Ti 2p peak. The Nb 3d XPS signal intensity of the Nb element decreased significantly. These results indicate that Ti and Nb elements segregated in the cathode material coating layer under a high voltage of 4.5 V, causing the Ti and Nb elements to segregate in different positions within the coating layer. The Ti element was located closer to the main electrode material, while the Nb element was located further away from the main electrode material.

[0076] Figure 4 To verify that the amorphous coating prepared in this embodiment promotes ion migration during the 4.5V LiCoO2 high-voltage charge-discharge cycle, we performed differential phase difference scanning transmission electron microscopy (DPC-STEM) analysis on the coated and activated cathode material sample 5 and the cathode material with lithium niobate coating. Figure 4 a and Figure 4 b Li 1+x Nb 1-x Ti x The DPC diagram and corresponding electromagnetic field distribution of the O3 coating layer show that charge carriers are uniformly dispersed at the positive electrode interface; while Figure 4 The DPC diagrams and corresponding electromagnetic field distribution diagrams of the c and 4d lithium niobate coatings show the presence of a carrier disappearance layer at the positive electrode interface. This illustrates the present invention's Li... 1+x Nb 1-x Ti x The presence of the O3 coating can also promote lithium-ion transport at the positive electrode interface.

[0077] Example 6 Application

[0078] To verify the performance of coated, coated but not activated, and coated and activated batteries at high voltage (4.3V) and 25°C, comparative LCO / LPSCl / In-Li samples and Li from Example 1 were compared. 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (unactivated) and Li 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (activated) was cycled within a voltage range of 4.3V, and the results are as follows: Figure 5 As shown.

[0079] from Figure 5 It can be seen from the coating of Li 1+x Nb 1-x Ti xO3 can improve the specific capacity of a battery to some extent, but the effect is not very significant. However, after activating it at 4.5V and then applying it to a higher voltage of 4.3V, the specific capacity of the battery is significantly improved, indicating that the elemental segregation that occurs during activation is beneficial to improving the specific capacity of the battery in the high-voltage operating range.

[0080] However, comparing the comparative LCO / LPSCl / In-Li sample and the Li sample from Example 1... 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (unactivated) was cycled within a voltage range of 4.5V, and the results are as follows: Figure 6 As shown, it was found that batteries made with only coated cathode materials without active activation already have very high specific capacity. This indicates that even without active activation, simply applying them to a 4.5V scenario and automatically activating them for a certain period of time can still improve the battery's specific capacity. In summary, activating the coating layer of the cathode material before use to induce titanium and niobium segregation is essential for improving the battery's specific capacity in the high-voltage operating range.

[0081] Example 7 Application

[0082] To verify the performance of coated, coated but not activated, and coated and activated batteries at low temperature (-20°C) and 4.3V, comparative LCO / LPSCl / In-Li samples and Li from Example 1 were compared. 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (unactivated) and Li 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (activated) was cycled within a working range of -20℃ and 4.3V, respectively. The results are as follows: Figure 7 As shown.

[0083] from Figure 7 It can be seen from the coating of Li 1+x Nb 1-x Ti x O3 can improve the specific capacity of a battery to a certain extent. Further activation at 4.5V followed by application to operating ranges of -20℃ and 4.3V significantly improves the specific capacity, indicating that elemental segregation during activation is beneficial for improving the specific capacity under low-temperature operating conditions. More importantly, battery samples assembled with uncoated cathode materials exhibit poor cycle life at low temperatures, with a significant decrease in specific capacity after 10 cycles, while those with Li coating show improved performance. 1+x Nb 1-x Ti xO3 materials can significantly improve cycle life, but cycle stability still needs improvement, with specific capacity fluctuating at different cycle counts. Furthermore, battery samples with activated coatings not only exhibit good cycle life with minimal change in specific capacity after 50 cycles, but also show significantly improved cycle stability compared to unactivated coated samples, with almost no change in specific capacity during each cycle, demonstrating high stability.

[0084] Example 8 Application

[0085] To verify the effects of coating, coating without activation, and coating with activation on battery performance at high temperature (80°C) and 4.3V, comparative LCO / LPSCl / In-Li samples and Li from Example 1 were compared. 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (unactivated) and Li 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (activated) was cycled within a working range of 80℃ and 4.3V, respectively. The results are as follows: Figure 8 As shown.

[0086] from Figure 8 It can be seen from the coating of Li 1+x Nb 1-x Ti x O3 can improve the specific capacity of a battery to a certain extent. Further activation at 4.5V followed by application to operating ranges of 80℃ and 4.3V significantly increases the specific capacity, indicating that elemental segregation during activation is beneficial for improving the specific capacity under high-temperature operating conditions. More importantly, battery samples assembled with uncoated cathode materials exhibit poor cycle life at high temperatures, with a significant decrease in specific capacity after 10 cycles, while those with Li coating show improved performance. 1+x Nb 1-x Ti x O3 materials can significantly improve cycle life, but cycle stability still needs improvement, with specific capacity fluctuating at different cycle counts. Furthermore, battery samples with activated coatings not only exhibit good cycle life with minimal change in specific capacity after 50 cycles, but also show significantly improved cycle stability compared to unactivated coated samples, with almost no change in specific capacity during each cycle, demonstrating high stability.

[0087] Example 9 Application

[0088] To verify the performance of uncoated, coated, and activated batteries at low temperatures, comparative LCO / LPSCl / In-Li samples and Li from Example 1 were compared. 1+x Nb1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (activation voltage 4.5) was cycled at -20℃, and the results are as follows: Figure 9 As shown. Figure 9 As can be seen, even at extremely low temperatures of -20°C, the activated all-solid-state lithium-ion battery still possesses excellent specific capacity and cycle performance.

[0089] Example 10 Application

[0090] To verify the performance of uncoated, coated, and activated batteries at high temperatures, comparative LCO / LPSCl / In-Li samples and the Li sample from Example 1 were compared. 1+x Nb 1-x Ti x O3@LCO / LPSCl / In-Li sample 1 (activation voltage 4.5) was cycled at 80℃, and the results were as follows: Figure 10 As shown. Figure 10 As can be seen, even at an extremely high temperature of 80°C, the activated all-solid-state lithium-ion battery still possesses excellent specific capacity and cycle performance.

[0091] Example 11 Application

[0092] The battery performance data of the coated and activated cathode material samples 2-4 prepared in Examples 2-4 at 25°C and 4.5V high voltage are as follows: Figure 11-13 As shown in the figure, the activated all-solid-state lithium-ion battery still possesses excellent specific capacity and cycle performance.

Claims

1. A solid-state lithium-ion battery cathode material, characterized in that, The all-solid-state lithium-ion battery cathode material includes an electrode material body and a coating layer covering the outer layer of the electrode material body, wherein the coating layer is made of Li. 1+ x Nb 1-x Ti x O3, where 0.1 ≤ x < 0.8, and the Ti and Nb elements in the coating layer are segregated, with Ti located closer to the main electrode material and Nb located further away from the main electrode material; based on the total weight of the all-solid-state lithium-ion battery cathode material, the outer coating layer has a mass of 0.25-2 wt% in the dry gel, and the thickness of the coating layer is 2-20 mm. nm; The electrode material of the all-solid-state lithium-ion battery cathode material is lithium cobalt oxide (LiCoO2); The preparation method of the all-solid-state lithium-ion battery cathode material includes the following steps: (1) Lithium source, niobium source and titanium source are added to an organic alcohol solution according to the stoichiometric ratio and dissolved, stirred continuously, and the electrode material body is added and stirred continuously to form a sol; (2) The sol obtained in step (1) is stirred and evaporated under constant temperature vacuum, and dried to form a gel; (3) The gel obtained in step (2) is calcined at constant temperature and cooled with the furnace to obtain the precursor of the all-solid-state lithium-ion battery cathode material; (4) The precursor of the all-solid-state lithium-ion battery cathode material obtained in step (3) is activated during the first voltage cycle charge and discharge process to cause the segregation of Ti and Nb elements to obtain the all-solid-state lithium-ion battery cathode material; The first voltage is greater than or equal to 4.5V and the activation time is 0.5-48h.

2. A method for preparing the all-solid-state lithium-ion battery cathode material according to claim 1, characterized in that, Includes the following steps: (1) Add lithium source, niobium source and titanium source to organic alcohol solution according to the stoichiometric ratio, stir continuously, add electrode material body and continue stirring to form sol; (2) The sol obtained in step (1) is stirred and the solvent organic alcohol is evaporated under constant temperature and vacuum, and dried to form a gel; and (3) The gel obtained in step (2) is calcined at a constant temperature and cooled in the furnace to obtain a precursor of all-solid-state lithium-ion battery cathode material; (4) The all-solid-state lithium-ion battery cathode material precursor obtained in step (3) is activated during the first voltage charge-discharge cycle to cause Ti and Nb element segregation, thereby obtaining the all-solid-state lithium-ion battery cathode material; the first voltage is greater than or equal to 4.5V, and the activation time is 0.5-48h.

3. The method for preparing the all-solid-state lithium-ion battery cathode material according to claim 2, characterized in that, In step (1), the lithium source is selected from lithium metal or organolithium, the organolithium including lithium ethoxide, lithium isopropoxide or tert-butyllithium, the niobium source is selected from organoniobium or NbCl5, the organoniobium including niobium ethoxide, the titanium source is selected from organotitanium, the organotitanium including isopropyl titanate, tetraethyl titanate or n-butyl titanate; the organic alcohol is selected from ethanol, propanol or ethylene glycol; step (1) is carried out in an argon atmosphere, the total stirring time is 1-24 h; the molar ratio of lithium source, niobium source, titanium source and organic alcohol is (1-5): (0.1-0.9): (0.1-0.8): (200-5000).

4. The method for preparing the all-solid-state lithium-ion battery cathode material according to claim 2, characterized in that, In step (2), the solvent is stirred and evaporated under high temperature vacuum at 40-120°C for 10-48 h.

5. The method for preparing the all-solid-state lithium-ion battery cathode material according to claim 2, characterized in that, In step (3), the calcination is carried out at a constant temperature under an oxygen flow atmosphere. The heating rate during the calcination process is 1-5℃ / min, the calcination temperature is 300-700℃, and the calcination time is 2-8 h.

6. The application of the all-solid-state lithium-ion battery cathode material according to claim 1 in a sulfide all-solid-state lithium-ion battery, characterized in that, The assembled battery operates within a wide temperature range of -20 to 80°C and a high voltage range of 2 to 4.5V.

7. A method for improving the performance of an all-solid-state lithium-ion battery in the high-voltage operating range, characterized in that, Using the all-solid-state lithium-ion battery cathode material as described in claim 1 as the cathode material of the battery can improve the specific capacity and cycle performance of the all-solid-state lithium-ion battery in the high voltage operating range of 2~4.5V.

8. A method for improving the performance of all-solid-state lithium-ion batteries within a wide temperature operating range, characterized in that, Using the all-solid-state lithium-ion battery cathode material as described in claim 1 as the cathode material of the battery can improve the specific capacity and cycle performance of the all-solid-state lithium-ion battery in a wide temperature range of -20~80℃.

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